R983032402 2FRM6A36-2X/25QRV-IN001 German Rexroth manual speed control valve

FAQ — Frequently Asked Questions

Q1: What is the difference between "A" and "B" versions of 2FRM6?

A:

• 2FRM6A…​ = Throttling in A → A₁​ direction (meter-in on Port A side). Stacked between directional valve and subplate on the A-port.

• 2FRM6B…​ = Throttling in B → B₁​ direction (meter-in on Port B side).

  For independent speed control on both extend and retract, one A-version and one B-version are typically stacked. The reverse flow always passes through a free-flow check valve with no restriction.

Q2: Why is an external drain (Y port) required and what if I don't connect it?

A:​ The pressure compensator spool​ needs a tank-pressure reference. The Y port must be plumbed directly to the reservoir with zero backpressure. If Y is blocked or sees backpressure, the compensator cannot regulate → flow becomes pressure-sensitive and unstable. Never omit or plug the Y port on a 2FRM valve.

Q3: How is this different from a Z2FS6 needle throttle valve?

A:​ The 2FRM6 has a pressure compensator​ maintaining constant ∆P across the metering orifice, so set flow stays constant despite load pressure changes​ on P or A ports. A Z2FS6 is a simple needle throttle — flow varies with ∆P. Use 2FRM when consistent actuator speed under varying load is critical; use Z2FS for basic, cost-sensitive throttling.

Q4: What does the "25Q" flow code mean in practice?

A:​ /25Q​ sets the maximum adjustable flow to approx. 25 L/min. This is beyond the usual /16Q max for NG6 — if your system truly needs >16 L/min through an NG6 flow control, verify the pressure drop in the datasheet. For better low-flow resolution, a smaller Q-range (/6Q, /10Q, /16Q) is preferable. If sustained flow exceeds 16–20 L/min regularly, consider stepping up to an NG10 (2FRM10) valve.

Q5: Why FKM (Viton) seals — is NBR not enough?

A:​ The V suffix = FKM seals, required for:

• Temperatures above +70°C (up to +80°C)

• Water glycol (HFC)​ or phosphate ester (HFD)​ fire-resistant fluids

  For standard mineral oil (HL/HLP) at normal temps, NBR is acceptable. The FKM version (this part R983032402) offers broader fluid compatibility and higher temp rating — select based on your actual hydraulic fluid.